Laundry detergents have been known for many years which contain surfactants, typically anionic surfactants, for cleaning fabrics such as clothing. Laundry detergents typically create suds during use in both hand-wash and automatic washing machine use. Especially during hand washing of clothes and fabrics, where the user is very involved with the washing process, a large volume of suds is initially desirable as it indicates to the user that sufficient surfactant is present, working and cleaning the fabrics.
However, while a large volume of suds is desirable during cleaning, it paradoxically typically takes between 3-6 rinses to remove such suds to the satisfaction of the person washing.
This adds up to a great amount of water which is used every day for rinsing around the world—typically about 5-10 tons of water per year per household in hand wash countries such as India, China, etc. As water is often a limited resource, especially in hand washing countries, the use of water for rinsing reduces the amount available for other possible uses, such as irrigation, drinking, bathing, etc. Depending on the location and the local practice, there may also be an added energy or labor cost involved with rinsing so many times and with so much water.
Suds suppressors are well-known in, for example, automatic dishwashing detergents and laundry detergents for front-loading washing machines. However, in a hand wash situation, the consumers are used to seeing suds during the wash, and if no suds are present, then consumers think that the laundry detergent contains insufficient surfactant to perform up to expectations. As typical suds suppressors do not distinguish between the wash and rinse conditions, they do not solve the problem of providing suds during use and yet reducing the need for rinsing.
During the rinse cycle, the typical laundry hand washer believes that if suds are still present, then there is surfactant residue that remains on the clothes, and therefore the clothes are not yet “clean” until the suds are not seen in the rinse. However, it has been found that fewer rinses can sufficiently remove surfactants and thus multiple rinsing is not needed. So, it has surprisingly been found that if consumer perception can be overcome, rinsing can be reduced with little or no adverse effects to the typical hand wash user, or fabrics.
Fabric treatment compositions and general use detergents have described, for example, the use of fatty acids in an acidic composition to allegedly initiate suds collapse in the rinse. However, such detergents would inherently possess impaired cleaning as compared to alkaline detergents and/or those which form an alkaline laundry liquor during use. This is because many typical fabric soils and stains are greasy soils. Alkaline conditions loosen up such soils and stains and therefore inherently clean such stains more efficiently. Thus, in an acidic composition containing a fatty acid, the cleaning efficiency and effectiveness are sacrificed in return for an alleged reduced need for rinsing. It is desirable to increase cleaning efficiency and effectiveness.
In addition, it is recognized that polyethyleneimine polymers in general are well known for use in detergents including laundry detergents. However, their use has typically been for their soil dispersancy and anti-redeposition properties.
Accordingly, as in many countries water and other resources is becoming ever more scarce the need exists for an effective way to reduce the amount of water used for rinsing during laundry without sacrificing cleaning efficiency and effectiveness.